从牵引变压器励磁电压变化导致励磁电流变化的角度分析处于运行状态的牵引变压器级联和应涌流的发生发展过程,以及级联和应涌流对牵引变压器差动保护的影响.在变压器空投时,起始涌流流过系统电阻时使公共节点上的电压出现非周期波动,从而引起处于运行状态变压器的励磁电压发生变化,导致级联和应涌流的产生；级联和应涌流中的直流分量是引起电流互感器饱和、进而导致牵引变压器差动保护误动的主要原因.动模实验结果表明:仅依靠综合谐波制动判据是无法准确识别级联和应涌流的,应增加电流互感器饱和的识别或使用不易饱和的电流互感器.%The physical mechanism of series sympathetic inrush between two traction transformers in traction substation is introduced by the relationship between magnetizing voltage and magnetizing current. The influence of series sympathetic inrush on the differential protection is also analyzed. Due to the particularity of power supply mode, the initial inrush caused by the energized transformer running across the system resistance results in the non-periodic fluctuation of voltage in the common node. The distorted voltages cause series sympathetic inrush. The DC component in the series sympathetic inrush causes the saturation of current transformer which is the main reason of the mal-operation in differential protection for traction transformer. Dynamic experiments show that a restraint criterion based on compositive harmonic content can not recognize series sympathetic inrush efficiently. A criterion of current transformer saturation detection or the current transformers that are not prone to saturate is recommended.
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